Levels of Organochlorine Pesticide Residues in Blood Plasma of Various Species of Birds from India

Concentrations of organochlorine pesticides (OCPs) were measured in blood plasma of 13 species of birds collected from Ahmedabad, India. Among the various OCPs determined, HCHs and its isomers had higher contribution to the total OCPs. Concentration of ∑HCHs varied from 11.4 ng/mL in White ibis Threskiornis melanocephalus to 286 ng/mL in Sarus Crane Grus antigone, while ∑DDT ranged between 19 ng/mL in Black Ibis Pseudibis papillosa and 147 ng/mL in Painted Stork Mycteria leucocephala. p,p′-DDE was accounted for more than 50% of total DDT in many of the samples analysed. However, a p,p′-DDT to p,p′-DDE ratio higher than one obtained for many species of birds indicates the recent use of DDT in this study region. The concentrations of cyclodiene insecticides, heptachlor epoxide, dieldrin and total endosulfan ranged from 15.8 to 296.2 ng/mL, below detectable level to 15 and 41.1–153.2 ng/mL, respectively. The pattern of total OCP load generally occurred in the following order: granivores < insectivores < omnivores < piscivores < carnivores. Although, the organochlorine residues detected in blood plasma of birds are not indicative of toxicity, the presence of residues in birds over the years (2005–2007) indicates continued exposure to organochlorine compounds. However, continuous monitoring is recommended to facilitate the early identification of risks to the survival of a species.